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SicariusMan writes "The age old question: do Guinness and other stouts' bubbles really sink, or is it an optical illusion? Well, some mathematicians have figured it out."Full paper via arXiv; From the article: "To analyze the effect of different glass shapes, the mathematicians modeled Guinness beer containing randomly distributed bubbles in both a pint glass and an anti-pint glass (i.e., an upside-down pint). An elongated swirling vortex forms in both glasses, but in the anti-pint glass the vortex rotates in the opposite direction, causing an upward flow of fluid and bubbles near the wall of the glass."

Yes but the math starts getting real dense midway in just about the time the author starts using 'yourmothersawhore' as a delta function. The last few pages seem to be completely unrelated work on chaos theory but I'm not sure that was intentional.

The underlying principle in science is to form a model and then test for confirmation or error. Clearly these dedicated professionals were testing in the name of science in case other forces were involved! In fact, I should do my part and run some tests of my own. I might also test some principles regarding gravity while I'm at it....

Twelve years ago an almost identical paper was on the office wall of a chemical engineering professor I had in college. I'm mostly kidding with my subject line - I expect there's novelty in the new paper and just want to point out that this has been used as a model system (probably many times) before now.

Twelve years ago an almost identical paper was on the office wall of a chemical engineering professor I had in college. I'm mostly kidding with my subject line - I expect there's novelty in the new paper and just want to point out that this has been used as a model system (probably many times) before now.

I believe you are referring to Md Nurul Hasan Khan. In 1999 he published a paper proving Guinness bubbles fall. As far as I know he was the first.

It's not because they're stouts, it's because nitrogen is used in making certain stouts (in this case, the title was better than the summary). Non-nitrogen stouts won't work. For example, Left Hand Brewery has a Milk Stout and a Milk Stout Nitro; only the Nitro has the cascade. Unless you find a nitrogen lager, there's really no experiment to be had.

Guiness is brewed in Ireland. The bubbles are made in Australia. When the can is opened the bubbles attempt to to up, but they are from Australia so they head the wrong way. Another pint of your finest, barkeep!

At the end of the paper they tantalisingly open the door to the possibility that there might exist a glass which would allow Guinness to settle more quickly. If such a glass were discovered, Irish barmen (well, all barmen really) would be able to pull pints more quickly. This means that fewer barmen would be required to man a bar so barmen would lose their jobs, increasing unemployment and probably plunging the country (perhaps the world) further into recession.
Risky research.

All pints of Guinness can be pulled quickly almost independently of the shape of the glass, the current two-stage pouring process was introduced as a marketing ploy some decades ago to make the beer somehow special. I'm not denying that the beer is special, only that it needs to be poured in any special way.